An Inhibitor of Death-Associated Protein Kinase 3 (DAPK3) Disrupts Hippo Signaling and Intestinal Epithelial Regeneration in Murine DSS-Induced Colitis.

BACKGROUND: Various signaling modules that affect epithelial wound healing are dysregulated in ulcerative colitis. Hippo signaling, acting downstream of cytoskeletal remodeling, is necessary for intestinal epithelial regeneration. Death-associated protein kinase 3 (DAPK3) is a regulator of actin cytoskeleton organization that also controls cellular proliferation and apoptosis responses. AIM: Recent genetic linkages between DAPK3 and the Hippo pathway suggest signaling coordination that has not been empirically evaluated. METHODS:  The impact of HS38, a DAPK3 inhibitor, on epithelial wound healing was examined using the dextran-sodium-sulphate (DSS) murine model of experimental colitis and Caco-2 human intestinal epithelial cell (IEC) monolayers. RESULTS: DAPK3 was significantly elevated in IECs isolated from DSS-treated mice, with cytoplasmic staining observed in epithelial crypts. The administration of HS38 to mice receiving DSS impeded the resolution of intestinal injury with attenuated IEC proliferation. HS38 treatment in DSS-colitis was also accompanied with decreased pS127, but not pS397, phosphorylation of Yes-associated protein (YAP). The data suggest that HS38 treatment, and hence DAPK3 inhibition, attenuates Hippo pathway signaling with subsequent nuclear enrichment of YAP. Additional analysis of single-cell RNAseq transcriptomic data from mucosal biopsies of UC patients reveals strong positive correlations between DAPK3 and YAP1 in the epithelial compartment. CONCLUSIONS: This study establishes DAPK3 as a novel factor in intestinal epithelial regeneration and ulcerative colitis progression by way of Hippo/YAP signaling. Nevertheless, the role that DAPK3 plays in different cell types will need further investigation to decipher the full consequence of DAPK3 involvement in epithelial homeostasis.

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Author Timothy Arthur James Haystead Pharmacology & Cancer Biology